i need help about a small mechanism?
I want to design a electromechanical mechanism which is potable and cell powered,a sensor mounted on a tiny plastic circle and the thing is attached to a shaft end.when started the shaft is slowly thrusting until the sensor on the shaft end is touched human skin the sensor send signal back to a microchip,the chip halt the thrusting shaft in case it squeeze the skin hard, next the NEEDLES around the sensor begin to work, they piercing through the skin then quickly spring out in case they cause much pain to people.
question 1:how to design the shaft thrusting mechanism?
question 2:is about the needles,how to pull them back quickly?
question 3:can it be wireless controlled?
pls help,any of ur suggestion would be greatly appreciated.